Q. A 1 m long wire is stretched without tension at $30℃\ $between two rigid supports. What strain will be produced in the wire if the temperature falls to $0℃$ ? (Given : $\alpha = 12\ \times 10^{- 6}\ K^{- 1})$
A) $36\ \times 10^{- 5}$
B) $64\ \times 10^{- 5}\ $
C) 0.78
D) 0.32
Explanation
(a) Strain = $\frac{\mathrm{\Delta}l}{l} = \frac{l\alpha t}{l} = \ \alpha t = 12 \times 10^{- 6} \times 30 = 36 \times 10^{- 5}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.